Safety

• Always wear laser safety goggles when using the laser, make sure that you have the correct goggles for the wavelength range of the laser

• Turn on the laser warning light indicator

• In any setup make sure that the beam path is terminated at the beam dump and also make sure there are not stray reflections

• Always place the beam block in front of the laser before making any changes to the optical beam path, this includes changing samples

Components

• 532nm DPSS pump laser

  • Since this laser does not have a built in power meter check the laser output power using the bolometer. While measuring power do not chop the beam.

• 532nm narrow bandpass filter to eliminate other wavelengths coming from the laser.

• optical chopper: improves signal to noise ratio (SNR).

• Detectors

  • Germanium detector, LN2 cooled to 77K, 500nm to 1500nm, set chopper to 100Hz

  • InGaAs detector, TE cooled upto -20C, 500nm to 1650nm, set chopper to 350Hz

  • InSb detector, LN2 cooled to 77K, 1500nm to 8000nm, set chopper to 350Hz

• SR830 Lock-in amplifier

• Acton SpectraPro 2500i spectrometer (0.5m optical path)

• Sample holder

  • The sample holder is connected to house vacuum. A toggle valve located above the PL setup turns on/off vacuum. Place the sample on the sample holder and turn-on vacuum to hold the sample firmly in place.

  • It also has precision micrometer to move the sample forwards and backwards for precision alignment.

Software

The most recent software (as of July 2015) is a python GUI application called SimplePL, written by Scott Maddox. It is available on Github.

Setting up a scan

• Turn on the laser.

  • Slowly ramp it up to the desired operating current, wait for the laser output power to stabilize.

  • Measure the incident power by removing the sample holder and letting the pump beam fall on the bolometer.

  • Repeat the same, but this time place the sample on the sample holder and the bolometer in the place of the beam dump to measure reflected power.

  • The difference of the above two powers will give the effective pumping power.

• Detector

  • Attach the appropriate detector at the exit slit of the spectrometer